This invention relates to an improvement to the apparatus for treating sewage and, in particular, sewage sludge, set forth in the above-identified copending application and original patent. More specifically, the present invention relates to apparatus for dispersing streams of prechanneled sludge to be treated throughout an oxygen-rich atmosphere by pressurized streams of gas directed toward and impinging on the streams of sludge.
Traditionally, sewage, and specifically sludge, has been difficult to treat because it is, almost by definition, extremely variable in composition. In addition to human liquid and solid organic waste, the sludge to be treated in accordance with the present invention may include industrial and commercial sludge which is susceptible to aerobic treatment. In general, the present invention provides a means and process for highly efficient interaction of sludge particles with oxygen, in the form of O.sub.2 gas and/or O.sub.3 gas.
The present invention preferably employs the use of hyperbaric vessels containing pressurized oxygen and the sludge, and provides means for increasing the surface area of sludge to be treated and the interaction time in which sludge is oxygenated compared to prior art apparatus and processes.
A further feature of the present invention resides in the substantially infinite adjustability of the various components of the apparatus and process so that they can be finely tuned at any time and adjusted automatically, semi-automatically and/or manually to treat different types, compositions and thicknesses of various sludges without requiring the use of alternate equipment.
The present invention is intended primarily for treatment of activated sludge, namely, waste from domestic, commercial and industrial sources which create a biologically degradable material. A batch of the pH adjusted waste to be treated is divided into small droplets and the droplets are dispersed within a pressure vessel where they are oxygenated by being exposed to oxygen (O.sub.2) and ozone (O.sub.3) for a substantial period of time. The Biological Oxygen demand (BOD) and the Chemical Oxygen Demand (COD) of the waste are substantially saturated and satisfied. The addition of ozone produces an almost complete destruction and elimination of coliform, fecal coliform, salmonella and other harmful bacteria from the batch of sludge being treated. Although the coliform and fecal coliform bacteria are not in themselves particularly harmful, when they are present, it is recognized that other harmful bacteria are present. Thus, when the coliform and fecal coliform bacteria are destroyed, it is an indication that the other harmful bacteria, which are more difficult to detect, are also destroyed.
The present invention is intended to be used in a large scale sewage treatment system for use in treating activated sludge which is generally too thick to be treated efficiently on a large scale basis by presently existing commercial equipment known to the inventor. The present invention can be incorporated with presently existing wastewater treatment plants. Most existing wastewater treatment plants are capable of producing sludge with a solid content of about one and one-half percent by weight. The present invention has been designed to treat sludge having a solid content of greater than four percent to about six percent by weight, more preferably from about five percent to about six percent. The process and apparatus are believed to be most cost effective with sludge having solids content of about five and one-half percent to six percent by weight.
The present invention is an improvement of the inventions illustrated, described and claimed in the prior filed copending application and original patent, the disclosures of which are hereby incorporated by reference herein. The sludge treating systems, processes and apparatus disclosed in the copending application and original patent enhanced the treatment of sludge compared to the systems, processes and apparatus previously known for that purpose. The present invention is a novel improvement of the inventions of the copending application and original patent. The improvement comprises an efficient means of dispersing the sludge in the reactor assembly by impinging streams of pressurized oxygen-rich gas upon streams of sludge dispersed from the channeling means of the first dispersing means of the apparatus of the copending application and original patent. Thus, this invention relates to novel second dispersing means for dispersing the sludge particles throughout the oxygen-rich atmosphere within the reactor assembly. The present invention preferably is used with the same systems and the same types of reactor assemblies used in the processes and apparatus disclosed in the copending application and original patent. Therefore, only the components of the overall system which are necessary to understand the present invention will be described herein.
It is believed that the gas impingement second sludge dispersing means of the present invention divides the sludge streams resulting from the channeling means of the first dispersing means into smaller and lighter weight particles having a greater surface area per volume ratio than the second dispersing means disclosed and claimed in the copending application or original patent. This increases the relative oxygenation of the particles and thus increases the efficiency of the oxygenation process. In addition, the lighter weight particles with the greater surface area descend slower throughout the oxygen-rich atmosphere in the upper portion of the reaction chamber, increasing interaction time in which the sludge is oxygenated compared to apparatus and processes of the prior art and of the copending application and original patent. The greater interaction time also enhances the overall efficacy of the process.